1. Field of the Invention
This invention relates to the processing of multi-filament and mono-filament synthetic fibers particularly polyester and nylon fibers with fiber lubricants which are applied as spin-finishes subsequent to the extrusion of the fibers from the spinneret.
2. Description of the Prior Art
In the production of polyester and polyamide filaments, a lubricant is generally added after extrusion of the fibers. The lubricant is essential in order that the subsequent processing of the emerging filaments can take place. The filaments are often subjected to a false twist process in which the fibers are stretched after being contacted with a heated metal plate. In addition to lubricity properties required to avoid breaking the fibers during such processing, relatively high oxidation stability is required to avoid breakdown of the fiber lubricants upon exposure to the temperatures encountered during the false twist processing operation. A further desirable requirement is improved biodegradeability. Because the lubricants of the invention are straight chain compounds, they have potentially greater biodegradeability than the branched chain 1,2-propylene oxide based fiber lubricants of the prior art.
It is known to utilize polyoxyethylene compounds as fiber lubricants to prevent fiber breakage during false twist processing. Such polyoxyethylene compounds including heteric polyoxyalkylene compounds derived from the random polymerization of polytetramethylene oxide (tetrahydrofuran) with either ethylene oxide or 1,2-propylene oxide and utilizing an acid or alcohol as an initiator are known from Tanizaki et al, Japenese Patent Announcement No. 213-1977. Use of an ethylene oxide cap on a heteric ethylene oxide and tetrahydrofuran copolymer provides a degree of flexibility in the preparation of fiber lubricants that permits more efficient variation of properties including water solubility while maintaining optimum lubricity in the fiber lubricants of the invention.
Polyether polyols prepared by reacting ethylene oxide and tetrahydrofuran are known from U.S. Pat. No. 4,038,296, U.S. Pat. No. 3,425,999 and U.S. Pat. No. 3,194,772.